[78-L] 84rpm on a side, 76rpm on the other

[Thomas HENRY]

Hello everyone,

Do some of you own records with a different speed on each sides ? Here is
an example with a 7' French Odeon (I'm the one who listed it on eBay) with
a 76rpm recording on a side and a 84rpm recording on the other:
http://www.ebay.fr/itm/RIGAUX-Les-Cloches-de-Corneville-78T-18cm-7inch-ODEON-INT-TALKING-MACHINE-/130893735057?pt=FR_VC_Vinyle&hash=item1e79dfe491#ht_500wt_1289
Is there an explanation for such a difference?
Thanks!

Thomas